A new measurement of the rare decay eta -> pi^0 gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

The A2 at MAMI collaboration Nefkens, B.M.K. ; Prakhov, S. ; Aguar-Bartolome, P. ; et al.
Phys.Rev.C 90 (2014) 025206, 2014.
Inspire Record 1297221 DOI 10.17182/hepdata.64169

A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0.03_tot) eV, are based on analysis of 1.2 x 10^3 eta->pi^0 gamma gamma decays from a total of 6 x 10^7 eta mesons produced in the gamma p -> eta p reaction. The present results for dGamma(eta->pi^0 gamma gamma)/dm^2(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence.

1 data table

D(WIDTH(ETA --> PI0 GAMMA GAMMA))/DM**2(GAMMA GAMMA) obtained from the data of 2007 and 2009 and their average. The error on the average is the total error.